Scientific Publications Database

Article Title: Cubic versus hexagonal - effect of host crystallinity on the T-1 shortening behaviour of NaGdF4 nanoparticles
Authors: Liu, Nan; Marin, Riccardo; Mazouzi, Yacine; Cron, Greg O.; Shuhendler, Adam; Hemmer, Eva
Journal: NANOSCALE Volume 11 Issue 14
Date of Publication:2019
Abstract:
Sodium gadolinium fluoride (NaGdF4) nanoparticles are promising candidates as T-1 shortening magnetic resonance imaging (MRI) contrast agents due to the paramagnetic properties of the Gd3+ ion. Effects of size and surface modification of these nanoparticles on proton relaxation times have been widely studied. However, to date, there has been no report on how T-1 relaxivity (r(1)) is affected by the different polymorphs in which NaGdF4 crystallizes: cubic (alpha) and hexagonal (beta). Here, a microwave-assisted thermal decomposition method was developed that grants selective access to NaGdF4, nanoparticles of either phase in the same size range, allowing the influence of host crystallinity on r(1) to be investigated. It was found that at 3 T cubic NaGdF4 nanoparticles exhibit larger r(1) values than their hexagonal analogues. This result was interpreted based on Solomon-Bloembergen-Morgan theory, suggesting that the inner sphere contribution to r(1) is more pronounced for cubic NaGdF4 nanoparticles as compared to their hexagonal counterparts. This holds true irrespective of the chosen surface modification, i.e. small citrate groups or longer chain poly(acrylic acid). Key aspects were found to be a polymorph-induced larger hydrodynamic diameter and the higher magnetization possessed by cubic nanoparticles.